Evaluation of "Global Warming: A Chilling Perspective"

Introduction

I'm going to read through the web page "Global Warming: A Chilling Perspective" and evaluate the various claims here. I've done some research on the subjects involved, but remember: Do not take my word for it. I'm not a climatologist. I might have made a big mistake. So, please go and look at the evidence yourself. There's lots of it out there. But always check the sources. If you ever read anything without solid references backing it up, you should always be sceptical about it.

Also, there are a number of claims made by the author of the web page which I could not find sources for. For each unfounded claim, I will point out that I could not find a source. If you find or have a source which supports a claim which I have said is unfounded, please share it by entering a link or citation to the source in the comments below. I would much rather prefer to set up the best arguments for both sides of the topic than to accidentally set up a 'straw man' argument which only misleads those involved.

Again, I must remind you: I'm not a climatologist. There are other, much more intelligent, people who have said the same thing: "Most of the observed increase in global average temperatures since the mid-20th century is very likely (≥ 90%) due to the observed increase in anthropogenic greenhouse gas concentrations." [1] Would you refuse to believe your doctor if they said that you had cancer?

They understand the science much better than I will ever understand it, so although I attempt to understand the climate science myself, I acknowledge that they will always have better insight about the climate science than me.

Why spend so much time?

It's quite simple. At the present time, I am convinced about these three things concerning anthropogenic global warming:

  1. There is a significant increase in mean global temperature occurring as we speak.

  2. Human activity is most likely (≥ 90%) the cause of most of this significant increase.

  3. If we do not act to reverse this significant increase in global temperature, our standards of living will significantly decrease in the near future -- probably within our lifetimes.

I'm not convinced of these things because somebody has told them to me and I have blindly believed them. There is overwhelming scientific evidence to support these three claims. Also, whenever anybody presents an argument to try and persuade me that any of these three claims are not true, when I examine their sources and arguments, they seem to fall apart. Because of this, I am convinced. However, I am always looking for a better argument that has a chance of dissuading me. I would much rather be convinced that our standards of living is not going to decrease. But unfortunately for me, I refuse to take seriously any arguments without proper references or arguments with serious logical flaws. So, if I come across a civil and seemingly reasonable argument against anthropogenic global warming, I will try to evaluate it against strict standards of evidence and logic (as I try to do with all arguments) and consider it.

So, why don't we start?

A Brief History of Ice Ages and Warming

The section begins with this paragraph:

Global warming started long before the "Industrial Revolution" and the invention of the internal combustion engine. Global warming began 18,000 years ago as the earth started warming its way out of the Pleistocene Ice Age-- a time when much of North America, Europe, and Asia lay buried beneath great sheets of glacial ice.

Let's have a look at the temperature variations over the past 12,000 years. This figure shows eight records of local temperature variability on multi-centennial scales throughout the course of the Holocene, and an average of these (thick dark line). The 2004 temperature variation is also pointed to. For information about the plotting methods and data sources of this figure, click here.

Figure 1. Image created by Robert A. Rohde / Global Warming Art

Now, let's have a closer look at the temperature variations over the past 1000 years. This figure is a comparison of 10 different published reconstructions of mean temperature changes during the last 1000 years and an instrumental record of mean temperature shown in black. The 2004 temperature variation is also pointed to. For information about the plotting methods and data sources of this figure, click here.

Figure 2. Image created by Robert A. Rohde / Global Warming Art

Now, let's have an even closer look at the temperature variations over the past 130 years. This figure shows the instrumental history of global mean temperature and its 5-year moving mean. For information about the plotting methods and data sources of this figure, click here.

Figure 3. Image created by Robert A. Rohde / Global Warming Art

As you can see from Figures 1, 2 and 3, there was an increase in temperature until 8000 years ago as the last glacial period ended. From 8000 years ago, there was a slow decrease in temperature at the rate of about 0.1°C per 1000 years. And then, from about 1910 until the present, there was a very fast increase in temperature at the rate of about 0.1°C per 10 years.

The temperature has increased more during the last 100 years than the temperature had decreased during the 8000 years before that.

This is why the terms "global warming" and "climate change" are quite misleading. There have always been shifts in temperature, both up and down. What is different is that we can now see that there has been a record-breaking increase in temperature since the beginning of the Industrial Age. This recent surge in temperature is part of what is called either "anthropogenic global warming" or "anthropogenic climate change". The distinction between "global warming" and "anthropogenic global warming" is that the "anthropogenic global warming" refers specifically to the global warming that has been caused by human activity.

Therefore, these claims that global warming started long before the Industrial Revolution are true but misleading. You could say that global warming started long before the dinosaurs and that claim would also be true. There has always been "global warming", but only since the Industrial Revolution has there been "anthropogenic global warming".

Earth's climate and the biosphere have been in constant flux, dominated by ice ages and glaciers for the past several million years. We are currently enjoying a temporary reprieve from the deep freeze.

This is true.

Approximately every 100,000 years Earth's climate warms up temporarily. These warm periods, called interglacial periods, appear to last approximately 15,000 to 20,000 years before regressing back to a cold ice age climate. At year 18,000 and counting our current interglacial vacation from the Ice Age is much nearer its end than its beginning.

Let's have a look at the temperature variations over the past 450,000 years. This figure shows Antarctic temperature changes during the last several glacial/interglacial cycles of the present ice age and a comparison to changes in global ice volume. The first two curves show local changes in temperature at two sites in Antarctica. The third curve shows a reconstruction of global ice volume. For information about the plotting methods and data sources of this figure, click here.

Figure 4. Image created by Robert A. Rohde / Global Warming Art

As you can see from Figure 4, there is regular cycle of about 80,000 to 120,000 years per cycle. The claim that "approximately every 100,000 years Earth's climate warms up temporarily" is correct.

However, the claim that interglacial periods "appear to last 15,000 to 20,000 before regressing back to a cold ice age climate" doesn't appear to be very accurate. I cannot find a source for this information. (If you can find a source, please leave a comment on this page with a link or citation to the source. Thanks.) In fact, due to the minimum of the eccentricity of the Earth's orbit around the Sun, it has been suggested that the current interglacial period may actually last another 50,000 years. [2] I cannot find any source to back up the claim that the interglacial period is nearing its end. (Again, if you can find a source, please leave a comment on this page with a link or citation to the source. Thanks.) The claims about how long interglacial periods usually are and how long the current interglacial period will last appear to be unfounded.

The claim that we are "at year 18,000 and counting" in our current interglacial period is incorrect. Technically, the current interglacial period only started about 11,700 years ago. [3] However, the author appears to have confused the end of the last glacial maximum with the beginning of the interglacial period.

Global warming during Earth's current interglacial warm period has greatly altered our environment and the distribution and diversity of all life.

The transition from the last glacial period to the current interglacial period did greatly alter our environment and the distribution and diversity of all life.

  • Approximately 15,000 years ago the earth had warmed sufficiently to halt the advance of glaciers, and sea levels worldwide began to rise.

Let's have a look at the sea level over the past 24,000 years. This figure shows sea level rise since the end of the last glacial episode. For information about the plotting methods and data sources of this figure, click here.

Figure 5. Image created by Robert A. Rohde / Global Warming Art
Correction: "Rio de Janeiro" should be "Rio de Janiero".

As you can see in Figure 5, there is a sharp increase in sea level between 14,600 and 13,000 years ago called Meltwater Pulse 1A. The sharp increase is assumed to be primarily caused by the break-up of the Laurentide Ice Sheet. [4] So the author's claim that the glacial advance had halted and that sea levels began to rise approximately 15,000 years ago is true.

  • By 8,000 years ago the land bridge across the Bering Strait was drowned, cutting off the migration of men and animals to North America.

It is correct that by 8,000 years ago the land bridge across the Bering Strait was drowned, but it has already started to form as early as 15,500 years ago. [5]

  • Since the end of the Ice Age, Earth's temperature has risen approximately 16 degrees F and sea levels have risen a total of 300 feet! Forests have returned where once there was only ice.

Technically, we are still in the Ice Age. However, the term "ice age" has come to colloquially refer to "glacial period". I think that the author intends to say "since the end of the last glacial period" instead. Also, as previously established, the author seems to be confusing the beginning of the increase in temperature with the beginning of the interglacial period.

The end of the last glacial period (the end of the Pleistocene period and the beginning of the Holocene period) is defined as 11,700 years ago [3].

We can see from Figure 4, since about 18,000 years ago (which is the date that the author has confused with the beginning of the current interglacial period) the temperature has increased by about 9°C (16.2°F). This figure does not seem significantly different from the temperature difference 11,700 years ago (which is the actual date that is the beginning of the current interglacial period). The author's claim of "approximately 16 degrees F" is correct.

We can see from Figure 5 that since about 11,700 years ago, the sea level has increased by about 60 meters (about 200 feet). However, since 18,000 years ago, the sea level has increased by about 120 meters (about 400 feet). Both values of 200 feet and 400 feet are significantly different from the author's claim of 300 feet. I'm unsure where the source is for the author's claim of "sea levels have risen a total of 300 feet" because my source of sea-level measurements do not match this figure. Regardless, it is safe to say that the author was trying to convey the point that the sea level had increased a significant amount, and the evidence supports this point.

During ice ages our planet is cold, dry, and inhospitable-- supporting few forests but plenty of glaciers and deserts. Like a spread of collosal bulldozers, glaciers have scraped and pulverized vast stretches of Earth's surface and completely destroyed entire regional ecosystems not once, but several times. During Ice Ages winters were longer and more severe and ice sheets grew to tremendous size, accumulating to thicknesses of up to 8,000 feet!.

Let's have a look at the maximum extent of glacial ice in the north polar area during the Pleistocene period. This figure shows the major land masses in yellow, the ocean in dark blue, the glacial areas in light blue and several city locations for reference. This figure is a reconstruction of a similar image by John S. Schlee at "Our Changing Continent" by the United States Geological Survey. For more information about this figure, click here.

Figure 6. Image recreated by Hannes Grobe / AWI
Recreated from an original image by John S. Schlee / USGS

Let's have a look at the thickness of the Laurentide ice sheet. This figure shows the topography of the Laurentide ice sheet 9,000 years ago, ranging from white (0m of ice thickness) to very dark blue (> 2500m of ice thickness). For more information about the plotting methods and data sources of this figure, click here.

Figure 7. Image modified by Allegra LeGrande / NASA GISS
Modified from an original image by A.E. Carlson et al.

As you can see from Figure 6, there were plenty of glaciers during the last glacial period. This author's claims about the vast amount of Pleistocenic glacial area is true.

As you can see from Figure 7, there were areas in the Laurentide ice sheet 9,000 years ago which were thicker than 2,500 meters (> 8,200 feet). The author's claim about glacial thickness ranging up to 8,000 feet is also true.

They moved slowly from higher elevations to lower-- driven by gravity and their tremendous weight. They left in their wake altered river courses, flattened landscapes, and along the margins of their farthest advance, great piles of glacial debris.

This is also true.

During the last 3 million years glaciers have at one time or another covered about 29% of Earth's land surface or about 17.14 million square miles (44.38 million sq. km.) . What did not lay beneath ice was a largely cold and desolate desert landscape, due in large part to the colder, less-humid atmospheric conditions that prevailed.

During the Ice Age summers were short and winters were brutal. Animal life and especially plant life had a very tough time of it. Thanks to global warming, that has all now changed, at least temporarily.

Let's have a look at the vegetation during the last glacial period. This figure shows a preliminary, broad-scale vegetation map for the world at the Last Glacial Maximum (approximately 25,000 to 15,000 years ago). This graph seems to be drawn from data from this article, but I cannot be sure. If you know if and why this information is inaccurate, please let me know so I can replace it with a reliable source.


Figure 8. Image reconstructed by the NGDC
Reconstructed from an original image by N. Ray et al. / NOAA

As you can see from Figure 8, during the last glacial maximum, the land surface of the Earth was covered with a large amount of ice sheet or other permanent ice, polar and alpine desert, tropical extreme desert and steppe tundra. It is quite clear that most of the Earth's land surface was cold and desolate, like claimed.

However the sentence "Thanks to global warming, that has all now changed, at least temporarily." is misleading. Although it is true that we are in an interglacial due to global warming, the sentence implies that all global warming is a good thing. While the interglacial period has allowed life on Earth to flourish, not all global warming is a good thing.

Let's have a look at the projected risks and impacts of global warming with further increased mean global temperature. This figure shows the increase in level of risk and impact in five categories of concern as mean global temperature increases. The first category addresses the potential for increased damage to or irreversible loss of unique and threatened systems, such as coral reefs, tropical glaciers, endangered species, unique ecosystems, biodiversity hotspots, small island states, and indigenous communities. The second category addresses increases in extreme events with substantial consequences for societies and natural systems such as increases in the frequency, intensity, or consequences of heat waves, floods, droughts, wildfires, or tropical cyclones. The third category addresses disparities of impacts among different regions, countries and populations. The fourth category addresses comprehensive measures of impacts. Impacts distributed across the globe can be aggregated into a single metric, such as monetary damages, lives affected, or lives lost. The fifth category addresses the likelihood that certain phenomena (sometimes called singularities or tipping points) would occur, any of which may be accompanied by very large impacts. These phenomena include the deglaciation (partial or complete) of the West Antarctic or Greenland ice sheets and major changes in some components of the Earth's climate system, such as a substantial reduction or collapse of the North Atlantic Meridional Overturning Circulation. For more information about the plotting methods and data sources of this figure, click here. This figure is technically out of date, having been replaced by this figure. I haven't found a copy of the figure yet which is embeddable in this web page. If you can find an embeddable copy of the updated figure, please let me know. Thanks.

Figure 9. Image created by J. B. Smith et al. / IPCC

As you can see from Figure 9, with increased temperature comes severely increased risks and impacts on not only the environment, but more importantly our global economy and ecology.

Let's have a look at some projections of the mean global temperature until 2100. Eight different projections have been overlaid to give you an idea of the general accepted range of projected mean global temperatures. For more information about the plotting methods and data sources of this figure, click here.


Figure 10. Image created by Robert A. Rohde / Global Warming Art

As you can see from Figure 10, without significant action as soon as possible, the mean global temperature is expected to increase by 2°C - 5°C above the 2000 mean global temperature by 2100. As you can see from Figure 9, and it's updated version, without significant action as soon as possible, many severe consequences will happen in the next 20 - 50 years, not hundreds of years as was previously thought.

In the 1970s concerned environmentalists like Stephen Schneider of the National Center for Atmospheric Research in Boulder, Colorado feared a return to another ice age due to manmade atmospheric pollution blocking out the sun.

Since about 1940 the global climate did in fact appear to be cooling. Then a funny thing happened-- sometime in the late 1970s temperature declines slowed to a halt and ground-based recording stations during the 1980s and 1990s began reading small but steady increases in near-surface temperatures. Fears of "global cooling" then changed suddenly to "global warming,"

-- the cited cause: manmade atmospheric pollution causing a runaway greenhouse effect.

Let's have a look at the current understanding of the major factors causing an impact on mean global temperature. This figure shows the the ability with which the U.S. Department of Energy PCM (Parallel Climate Model) global climate model is able to reconstruct the historical temperature record and the degree to which the associated temperature changes can be decomposed into various forcing factors. For more information about the plotting methods and data sources of this figure, click here.

Figure 11. Image by Robert A. Rohde / Global Warming Art

Let's take a look at the number of scientific publications with mean global temperature predictions which were published in the late 1960s and 1970s. This figure shows the number of papers published between 1965 and 1979 classified as predicting, implying, or providing supporting evidence for future global cooling, warming, and neutral mean global temperature change. For more information about the plotting methods and data sources of this figure, click here.

Figure 12. Image by Thomas Peterson, William Connolley, John Fleck / American Meteorological Society

As you can see in Figures 3 and 11, there was a discernible but slight decrease in the mean global temperature from about the 1940s until the 1970s. The author claims that "[i]n the 1970s concerned environmentalists like Stephen Schneider of the National Center for Atmospheric Research in Boulder, Colorado feared a return to another ice age due to manmade atmospheric pollution blocking out the sun." The author appears to be referring to a paper co-authored by Stephen Schneider and S. Ichtiaque Rasool which was published in Science in July 1971. In this paper, titled "Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate", the conclusion was reached that a quadrupling of global aerosol concentrations (its modeled forcing shown as "sulfate" in Figure 11) could decrease the mean global temperature by as much as 3.5°C and that if sustained over several years, such a temperature decrease could be sufficient to trigger an ice age. [6] However, problems with their paper were raised quickly both by the authors Rasool and Schneider themselves [7] and by others. [8] It was later concluded that the original paper by Rasool and Schneider overestimated the forcing effects of aerosols on cooling and underestimated the forcing effects of carbon dioxide on warming. [9] [10]

As you can see in Figure 12, there was a greater or equal number of scientific publications predicting an increase in the future mean global temperature trend than there were predicting a decrease for each year between and including 1965 and 1979. By looking at Figure 12 and by considering that scientists have been making predictions that increased CO2 levels could increase mean global temperature since 1896 (Svante Arrhenius predicted that a doubling of the atmospheric CO2 concentration could raise the mean global temperature by 4 - 5°C) [11], we can tell that there was always more scientists which agreed with predictions of global warming than scientists which agreed with predictions of global cooling.

Due to the large number of different factors which cause variations in the mean global temperature, it can be expected that there could be competing and conflicting forces. In this case, an increase in sulphur aerosol pollution causes an increase in global dimming (where particles in the atmosphere reflect more sunlight away from the planet) causing an increase in global cooling, while an increase in CO2 pollution causes an increase in global warming. As you can see in Figure 11, the acceleration of CO2 concentration has overwhelmed the other forcing factors.

The author is correct in claiming that between 1940 and the 1970s, the global climate appeared to be cooling. However, to state the "[f]ears of 'global cooling' then changed suddenly to 'global warming'" is false and misleading. Predictions of anthropogenic effects causing global warming have existed well before any 'fears' of global cooling were formed. Scientific opinion has always favoured predictions of future global warming instead of future global cooling and to imply that there was a scientific consensus (or even a majority) in support of predictions of future global cooling only serves to mislead the reader and distort honest debate on the topic of anthropogenic global warming.

References

  1. Climate Change 2007: The Physical Science Basis. Summary for Policymakers Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Accessed on 2009-12-25.
  2. Berger, A., and M. F. Loutre. 2002. "Climate: An Exceptionally Long Interglacial Ahead?" Science 297.1287-8.
  3. International Statigraphic Chart 2009 International Commission on Stratigraphy. Accessed on 2009-12-25.
  4. Gornitz, V. 2009. Encyclopedia of paleoclimatology and ancient environments. Springer. p. 890 (Table S1). ISBN 9781402045516.
  5. Pielou, E. C. 1991. After the Ice Age: The Return of Life to Glaciated North America. University of Chicago Press. p. 19. ISBN 0226668126.
  6. Rasool, S. I. and S. H. Schneider. 1971. "Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate" Science 173.138-41.
  7. Rasool, S. I. and S. H. Schneider. 1972. "Aerosol concentrations: Effect on planetary temperatures." Science 175.96.
  8. Charlson, R. J., H. Harrison, and G. Witt. 1972. "Aerosol concentrations: Effect on planetary temperatures." Science 175.95-6.
  9. Schneider, S. H. and C. Mass. 1975. "Volcanic dust, sunspots, and temperature trends." Science 190.741-6
  10. Weart, S. The Discovery of Global Warming Accessed on 2009-12-25.
  11. Arrhenius, S. 1896. "On the Influence of Carbonic Acid in the Air Upon the Temperature of the Ground." Philosophical Magazine 41.237-76.
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